Alginic acid is a polysaccharide. Alginic acid is generally comprised of mannuronic acid units (hereinafter referred to as “M”) and guluronic acid units (hereinafter referred to as “M”), which are randomly linked as linear long-chain molecules. Natural alginic acid (such as brown algae) has a G to M molar ratio of 0.2 to 2.5 and a molecular weight of 100,000 to 1,500,000 Da.
Alginic acid is usually used for products such food, medicine, textile, printing and dyeing, paper making, daily chemical and the like as a thickening agent, emulsifier, stabilizer, adhesive, sizing agent, etc. Researches have already shown that degradation of alginic acid will generate an alginic acid having low molecular weight, for example, from 5,000 Da to 20,000 Da in average with pharmacological activity.
For example, CN 1157415C has disclosed salts of alginic acid with low molecular, which have an average molecular weight of 5,000 to 20,000 Da, while most of which have a molecular weight of 1,000 to 30,000 Da, and a Ubbelohde intrinsic viscosity number between 3 and 20, wherein the salt-forming ions of the said alginate are pharmaceutically acceptable cations. The said salts of alginic acid with low molecular have a certain effect on reducing blood pressure and blood glucose.
However, the activity of alginic acid or its salts with lower molecular weight in reducing blood pressure and blood glucose still needs to be proved, and research and development still need to be made to find whether they have other pharmacological actions. Moreover, due to variations in sources of raw material and preparation conditions, it is difficult to ensure different batches of the prepared alginic acid with low molecular weight or its salts to have excellent uniformity.